1. Field of the Invention
This invention relates to a method of logging subterranean reservoirs traversed by well bores, particularly hydrocarbon-containing reservoirs. In one aspect this invention relates to a method for determining the amount of residual oil in an oil bearing formation employing logging techniques. In yet another aspect, this invention relates to a method for determining the amount of residual oil present in subterranean reservoirs traversed by well bores wherein such residual oil saturation properties are detected by the use of a log-reservoir flood injection-log technique.
2. Brief Description of the Prior Art
The importance of determining residual oil in place by means of sub-surface logging techniques has been recognized for some time. At the present new oil fields are becoming more difficult to discover and more attention is being given to secondary and tertiary methods for oil recovery in oil fields. However, prior logging techniques have required the use of radio-active materials or substantial knowledge of the subterranean formation such as porosity, lateral penetration, make up of the formation, and the like, if one is to obtain reliable information from such logging techniques. Therefore, while numerous methods have been and are being used to determine the amounts of residual oil present in reservoir formations, all of the prior art methods, regardless as to whether they employ core analysis, well testing, well logging, and the like, have certain limitations. Pitfalls and the rather unsatisfactory accuracy of the results using these conventional techniques have created a serious problem for the oil industry. Because of the high costs in recovering such residual oil through secondary or tertiary means, it is desirable and of utmost importance that an accurate, dependable method be developed for determining the amount of residual oil remaining in such formations. Until the present invention, there was no satisfactory method for accurately and inexpensively determining the amount of residual oil.